Donovan had spinal muscular atrophy (SMA), a rare disorder caused by a defective gene; the illness destroys the nerves that control muscles. Babies with the most severe form of the disorder typically don't live past their second birthday.

"We were devastated," Weisgarber says, recalling the diagnosis. "It was definitely the worst time of our lives."

Zolgensma, a new drug approved by the FDA Friday, costs more than $2 million.

Novartis

But then doctors told Laura and her husband, Matthew, about an experimental gene therapy that was being tested for SMA. So they agreed to let them infuse Donovan with genetically modified viruses carrying healthy copies of the gene he needed.

Donovan slowly started to improve. Donovan still needs a wheelchair to get around and a feeding tube for nutrition. But otherwise he's doing well, his mother says.

"He loves going outside. He loves playing with his family. He goes to preschool," Weisgarber says. "He gets to do a lot of normal things. It's amazing."

And Donovan isn't alone. The gene therapy — called Zolgensma —has been saving other babies with spinal muscular atrophy.

"We saw just remarkable results for these kids," says David Lennon, president of AveXis,Inc., of Bannockburn, Ill., the company that developed Zolgensma. The company is owned by drug giant Novartis. (AveXis connected NPR with the Weisgarber family.)

Based on the AveXis studies, the FDA approved Zolgensma Friday, making it only the second gene therapy ever approved for a genetic disorder. There are currently around 700 patients eligible for the treatment, according to Novartis, and roughly 30 babies are born each month with the disease.

Novartis set the price at $2.125 million but offers insurers the ability to pay $425,000 a year for five years.This price tag makes Zolgensma the most expensive drug ever approved.

"We have been slowly subjected to price increases the same way the frog in the boiling water is slowly boiled to death," Bach says.

Insurers are expected to cover the cost. The company says payment plans will be available.

AveXis president Lennon acknowledges the numbers might seem shocking. But he argues the drug is easily worth it. The only existing treatment for spinal muscular atrophy, a drug called Spinraza, costs hundreds of thousands of dollars a year. Zolgensma hopefully will be aone-time, life-saving treatment.

"We're talking about a lifetime of benefit being condensed down into a one-time treatment," Lennon says. "We're not used to thinking about this that way. We're used to a system of a chronic medication where we spread things out over years if not decades."

The drug is delivered as a single one-time dose to address the genetic root cause of the disorder, the company says, producing long-term effects.

From that point of view, Lennon calls it "highly cost-effective" and a "fair and reasonable price."

Drug companies need to be able to recoup the costs of developing life-saving, cutting-edge treatments, he says, if they're going to be encouraged to find new breakthroughs.

"We're continuing to reinvest in new therapies beyond Zolgensma into the next wave of gene therapies that are going to hopefully offer cures for other diseases," Lennon says.

At one point, Novartis said publicly that the price of Zolgensma might be as high as $5 million.

"Insurers were going to cover Zolgensma no matter the price," says Dr. Steven D. Pearson, president of the nonprofit Institute for Clinical and Economic Review in Boston, an independent research group that studies drug pricing. "It is a positive outcome for patients and the entire health system that Novartis instead chose to price Zolgensma at a level that more fairly aligns with the benefits for these children and their families."

ICER estimated that a reasonable price would be between $1.2 and $2.1 million per treatment, based on an estimate of years of quality life valued at $100,000 to $15o,000 per year.

Donovan's parents didn't have to pay for the treatment because their son was part of a research study. But they think Zolgensma is worth the price.

"I understand that it can be shocking when you see a price tag on a treatment like this," Weisbarger says. "But giving someone a life — someone that would have died in infancy or early childhood the opportunity to live into adulthood — I think that's a valuable investment."

The company says it has been manufacturing the drug since January and supplies of the drug will be released "shortly," Lennon says.

Copyright 2019 NPR. To see more, visit https://www.npr.org.

MARY LOUISE KELLY, HOST:

The Food and Drug Administration approved a new form of therapy today for a devastating genetic disease. It is providing hope for babies born with this rare but often fatal disorder. But as NPR health correspondent Rob Stein reports, at more than $2 million, the treatment is the most expensive drug ever approved.

ROB STEIN, BYLINE: When Donovan Weisgarber was born, he seemed perfectly healthy. But within weeks, his mom, Laura, says it became clear something was wrong - terribly wrong.

LAURA WEISGARBER: It was when he was about 1 month old - was when we started to notice some symptoms.

STEIN: He started getting really fussy, stopped squirming and got weaker and weaker. Turns out Donovan had a genetic disorder, spinal muscular atrophy. It was destroying the nerves that control his muscles. Many babies don't live beyond their second birthday. It's the most common genetic cause of death among infants.

WEISGARBER: We were devastated obviously. Yeah, you know, obviously you're devastated. It was definitely the worst time of our lives.

STEIN: But then doctors told Laura and her husband, Matthew, about something new. They might be able to replace the defective gene killing Donovan with a new type of gene therapy. So they agreed to let doctors infuse Donovan with genetically modified viruses carrying healthy genes into his body. Donovan slowly started to improve, and three years later, Donovan still needs a wheelchair and a feeding tube but otherwise is doing great, his mom says.

WEISGARBER: You know, he loves going outside. He loves playing with his family. He goes to preschool. So yeah, he gets to do a lot of normal things. So it's just - I mean, it's amazing.

STEIN: And Donovan isn't alone. This gene therapy has been saving other babies with spinal muscular atrophy. David Lennon is the president of AveXis, the company that makes what's now called Zolgensma.

DAVID LENNON: First of all, a hundred percent of the kids survived. And this is a population where 92% of the kids would expect to have died or be on permanent ventilation by the time they're 20 months old. But then we also saw additional things. A lot of these kids could swallow. Seventy-five percent of these kids were able to sit. And we actually had a few kids who were able to stand and walk independently.

STEIN: Based on these results, Lennon says the company is justified in setting the price at $2.125 million for each child, which would make it the most expensive drug ever approved. And that price tag is making a lot of jaws drop.

BACH: It's just alarming that we have gotten to a point where, you know, any treatment that is a product of this collective scientific enterprise that has grown out of the Human Genome Project that was publicly funded has now been captured by a single drug company and is now going to turn around and charge potentially millions.

STEIN: Bach says it's just the most extreme example of how drug prices are draining resources from society.

BACH: We have been slowly subjected to price increases the same way the frog in the boiling water, you know, is slowly boiled to death.

STEIN: Now, Lennon acknowledges the price might seem shocking. But he argues it's worth it. The only existing treatment for spinal muscular atrophy costs hundreds of thousands of dollars a year, and this will hopefully be a one-time, lifesaving treatment that will last a lifetime.

LENNON: What we're talking about and we have to remember is we're talking about a lifetime of benefit being condensed down into a one-time treatment. We're not used to thinking about this that way. We're used to a system of chronic medication where we spread costs out over years, if not decades.

STEIN: Drug companies need to be able to recoup the costs of developing lifesaving, cutting-edge treatments, Lennon says, if they're going to be encouraged to find new breakthroughs. Donovan's parents didn't have to pay because their son was part of a research study, but they think the treatment is worth the price.

WEISGARBER: Giving someone a life, someone that would have died in infancy or early childhood the opportunity to live into adulthood, I mean, I don't know. I think that's valuable. I think it's a valuable investment.